In recent years, communication apparatuses used for mobile communication are being used in higher frequency bands in order to handle services transmitting and receiving data utilizing wireless communication such as WLAN (wireless local area network) or the like. Along with the higher frequencies of these communication apparatuses, the electronic parts used for the same are also being required to be able to operate at higher frequencies.
As key parts of such communication apparatuses, there are surface acoustic wave devices (SAW device). A SAW device is used as, for example, an element for configuring a ladder-type surface acoustic wave filter (SAW filter). Such a filter is excellent in power durability performance and is being used in an antenna splitter etc. in a frequency band in which it operates at a high frequency. However, with a conventional ladder type SAW filter, it was difficult to sufficiently secure electric characteristics demanded by a communication apparatus operating at a high frequency, such as an attenuation characteristic in the vicinity of the pass band, an insertion loss characteristic of the pass band, an attenuation amount out of the pass band or the like.
For this reason, a SAW device using a multimode type SAW filter, capable of operating at a high frequency, and improved in electric characteristics such as the attenuation characteristic in the vicinity of the pass band, attenuation amount out of the pass band, or the like has been proposed. However, sufficient power durability performance is liable not to be able to be secured when a conventional multimode type SAW filter is operated at a high frequency.
FIG. 9 and FIG. 10 are plan views of principal parts showing conventional SAW devices. Here, as shown in FIG. 9, in order to sufficiently secure power durability performance, there is proposed a SAW device in which IDT (inter digital transducer) electrodes configuring a multimode type SAW filter, formed on a piezoelectric substrate, and exciting a SAW are serially divided to divide power supplied to the IDT electrodes (see for example Patent Document 1).
Further, as shown in FIG. 10, as another means for securing power durability performance, there is proposed a SAW device in which a plurality of surface acoustic wave elements (SAW elements) configuring a multimode type SAW filter are connected in parallel to disperse power supplied to the SAW elements (see for example Patent Document 2).
In the multimode type SAW filters shown in FIG. 9 and FIG. 10, by arranging narrow pitch sections at which an electrode finger pitch of the IDT electrodes becomes narrow at portions at which IDT electrodes adjoin each other, a reduction of loss and a broadening of the band of the SAW device are realized. In this case, if energy is concentrated at the electrode finger narrow pitch sections, stress is concentrated at the electrode finger narrow pitch sections.
Accordingly, it has been desired to provide a surface acoustic wave device and a communication apparatus excellent in power durability performance and capable of operating at a high frequency.    Patent Document 1: Japanese Patent Publication No. 2006-311180    Patent Document 2: Japanese Patent Publication No. 2004-194269